The invention relates to connector plugs for light transmitting fiber cables which enter the connector plugs from opposite ends and are releasably engaged such that the fiber ends abut one another.
Connector plugs for light transmitting fiber cables serve to interconnect the ends of two light transmitting fiber cables as well as to connect a cable to a converter, for example. Such optical connector plugs are necessary members of optical light transmission systems, which have to fulfill specific requirements. In addition to a secure connection there should be little attenuation which is dependent on a good number of factors. The low attenuation must remain unchanged over a large number of connecting cycles wherein 100 plug-in cycles is considered to be the minimum.
The attenuation at the joints of two fibers depends on
(a) the dislocation of the two fibers PA1 (b) the gap between the face surfaces PA1 (c) the angle deviation.
The dislocation of two fibers is the distance between the parallel axes of the abutting fibers and the angle deviation from parallel at which the fibers intersect.
There are several fiber cable connectors so designed as to maintain fiber dislocation and angle deviation of such connectors as small as possible. The best known connector supports the glass fiber cable with its coating in a mounting member, wherein the glass fiber is clamped at the entering end for axially positioning the fiber. At its free end the glass fiber is stripped and supported in a centering member. Two of those centering members with the glass fiber ends disposed therein are inserted coaxially into a cylindrical housing from its opposite ends until the glass fiber ends abut. In this position the centering members are then fixed by screws or cement.
Assembly of such a connector, however, is difficult since the coating has to be removed from the front end of the glass fiber and the glass fiber has to be introduced into the centering member so that the glass fiber is properly inserted into a connector crystal and is properly retained in abutment with the face of the connector crystal by means of the crimping sleeve. Apparatus and methods for the removal of the plastic coating are already known with which it is relatively easy to slip the coating off the fiber, especially if the coating is heated. If the coating, however, consists of a silicon layer, it is important that the coating is completely removed since otherwise no proper adhesion between the glass fiber and the cement will be obtained.
The light conducting fibers as presently used, those with glass as well as those with plastic coatings, and also those with glass and plastic coatings, are all difficult to insert into the centering member. The glass coating without additional plastic coating, however, has the advantage that it need not be removed from the fiber at the connecting point but is simply broken or cut off together with the glass fiber.
In place of the connector crystal into whose central opening the glass fiber is to be introduced, centering devices have become known which support the glass fibers in centering elements. Such centering elements are, for example, fiber rods of relatively large cross-sectional areas which are surrounded by a sleeve and support the glass fibers concentrically therein or members with V-shaped grooves by whose side walls the glass fibers which are to be interconnected are supported. With such connectors it is practice to leave a gap at the point of fiber jointure which gap is filled with an immersion (wetting) oil in order to eliminate, to some extent, the consequences of inaccuracies such as fiber dislocation, gap size between fiber faces and angle deviations.
It is obvious that such fiber cable connectors need to be manufactured with great accuracy and that, considering their use of relatively rare materials, they are quite expensive.
It is the main object of the present invention to provide such a light conducting cable connector which, to a large extent, eliminates the causes of high attenuation, that is, fiber dislocation, gaps between fiber faces and angle deviations and which may be manufactured at reasonable expense from easily available materials and without the requirement for high precision work.